The present invention relates to a process for cleaning of pipe lines, especially ventilation pipes and ventilation ducts of large cross-sectional area, in buildings, by means of a cleaning means, which is connected via a supply conduit to a source of pressure medium, for example a compressed air compressor, and which cleaning means exhibits one or more nozzle openings which are directed backwards towards the supply conduit at an acute angle relative to a centre line which extends through the fastening of the supply conduit in the cleaning means. The present invention is also relates to a nozzle opening in the form of a mainly continuous annular gap, which extends along the periphery of the cleaning means and which is connected to the supply conduit and the source of pressure medium, the medium being made to discharge through the annular gap and partly clean inner walls of the line, and partly, by way of forces of reaction from the discharging medium, make the cleaning means move into the pipe line.
The invention also relates to a cleaning arrangement for carrying out the process, comprising a cleaning means in the form of a rear piece, and a front piece detachably mounted on the rear piece, for providing a nozzle opening in the form of a mainly continous annular gap which is directed backwards towards the supply conduit at an acute angle towards a centre line which extends through the fastening of a supply conduit in the cleaning means, and the cleaning means is connected to a source of pressure medium via the supply conduit.
Norwegian Patent No. 41.358. discloses a nozzle head for cleaning pipes and passageways. The nozzle head which comprises an annular continous gap near the periphery of the head, is connected to a hose supplying pressure fluid, and the fluid is directed backwards through the gap to clean the pipe and move the nozzle head further along the pipe. However, the nozzle head of this prior art is intended and designed also to rotate and to float about the middle of the pipe in effecting the cleaning operation. Thus it is not intended to be in close contact with the pipe inner wall as is the case with the present invention. Another example of this kind of cleaning nozzle head is known from U.S. Pat. No. 1,587,194.